Since at least the 1960s, astronauts and satellites have been snapping photos of planet Earth from on high. While many of these photos possess an intrinsic beauty, some hold important clues about the goings-on of the inhabitants below. In this episode of The Countdown, we bring you five images that speak loudly about the challenges facing the human race.

Video credits - Host/writer: Sophie Bushwick, production assistant: William Herkewitz, editor: Kathryn Free, producer: Eric R. Olson